Deterioration of the brain sneaks up on most of us. Some people may notice a modest decline in their ability to learn new things and retrieve information, such as remembering names. They may perform worse on complex tasks of attention, learning and memory than would a younger person.

However, if given enough time to perform the task, the scores of healthy people in their 70s and 80s are often similar to those of young adults. In fact, as they age, adults often improve in other cognitive areas, such as vocabulary and other forms of verbal knowledge.

In the past several decades, investigators have learned much about what happens in the brain when people have a neurodegenerative disease such as Parkinson's disease, Alzheimer's disease (AD) or other dementias. Their findings also have revealed much about what happens during healthy aging. Researchers are investigating a number of changes related to healthy aging in hopes of learning more about this process so they can fill gaps in our knowledge about the early stages of AD.

The human brain has an extraordinary demand for energy — 20 to 30 percent of the body's energy budget. In the course of normal aging, the supply of sugars to the brain may be reduced in people with neurodegenerative diseases or mental disorders, or in periods of physiological stress. This can lead to a reduction in the brain's energy reserves, which in turn can lead to cognitive decline and loss of memory.

But new research on mice shows the brain's energy reserves can be increased with a daily dose of pyruvate, a small energy-rich molecule that sits at the hub of most of the energy pathways inside the cell. These results need to be replicated in humans but could ultimately lead to clinical applications.

According to lead author Heikki Tanila, professor of molecular neurobiology at the A. I. Virtanen Institute of the University of Eastern Finland, the new study shows long-term dietary supplementation with pyruvate increases the energy reserves in the brain at least in mice in the form of the molecules glycogen, creatine and lactate. In fact, dietary supplementation with pyruvate also changed the behavior of the mice in positive ways.

For example, the mice became more energetic and increased their exploratory activity, suggesting these behavioral changes are directly due to the effect of pyruvate on brain function. The dose necessary to achieve these effects was about 800 mg pyruvate per day, which corresponds to about 10 g per day in humans, administered to the mice in normal food over a period of 2.5 to 6 months. A single large dose of pyruvate injected directly into the blood stream had no detectable effect.

On another note, the positive response to dietary supplementation with pyruvate was also found in a strain of transgenic mice called APPswe/PS1dE9, often used as an animal model for the study of Alzheimer's disease. These mice exhibit many of the same symptoms as people with AD, such as the deposition of protein plaques in the brain, neurodegeneration and cognitive decline.

These results show promise that pyruvate might also benefit people with neurodegenerative disorders such as AD and Parkinson's. Pyruvate supplementation may prove beneficial as an activating treatment for elderly persons and in therapies for alleviating cognitive decline related to aging, neurodegenerative disease or mental disorders.

According to the researchers, pyruvate supplementation warrants further studies in humans.